AIAB : AUC settlement multiple line item

Hi

We are creating settlement rule for auc , having multiple line item . Initial execution of AIAB, shows the line items as below.

I select all of these line items and then in the next screen, I provide the below.

Then I come back and execute the settlement.

I get the below error. Just wanted to know, how AIAB relates each line item in AUC to the amounts entered in the "Maintain settlement rule screen"

As I selected all the line item of AUC, I thought the entire amount is 3120, which I can distribute among two items. Please let me know, that, if there are three line items should I always enter 3 items in the settlement rule section? What if, I wanted to maintain 4 receivers in total for the 3 line items.

Please let me know.